Rotary heat exchanger with ribbed inner liner of higher thermal conductivity than outer shell



Feb. 6, 1968 J. F. cox, JR

ROTARY HEAT EXCHANGER WITH RIBBED INNER LINER OF HIGHER THERMALCONDUCTIVITY THAN OUTER SHELL Filed Aug. 1, 1966 2 Sheets-Sheet lINVENTOR. mm A 602" JZ WMK m 147' f GENE V3 Ffib W8 J. F cox, JR 3 9ROTARY HEAT EXCHANGER WITH RIBBED INNER LINER OF HIGHER THERMALCONDUCTIVITY THAN OUTER SHELL Filed Aug. 1, 1966 2 Sheets-Sheet 2 m2jiza I 92 p i, 7'00 92 g l \Q F \4 m/ v INVENTOR. Jzz/Zmz f 6'01 UnitedStates Patent 3,367,042 ROTARY HEAT EXCHANGER WITH RIBBED IN- NER LINEROF HIGHER THERMAL CONDUC- TlIVlTY THAN OUTER SHELL Julian F. Cox, In,Newport News, Va., assignor to Newport News Shipbuilding and Dry DockCompany, Newport News, Va., a corporation of Virginia Filed Aug. 1,1966, Ser. No. 569,221 Claims. (Cl. 34124) ABSTRAQT OF THE DESCLOSURE AYankee drier for drying a web of paper comprises a generally cylindricalshell closed at opposite ends thereof and journalled for rotation aboutits longitudinal axis. Means is provided for introducing steam into thedrier and exhausting same therefrom. The shell includes an outer shellportion and a liner disposed inwardly thereof and in contact therewith,the liner being formed of a material having higher thermal conductivitythan the outer shell portion. A plurality of spaced radially inwardlyextending ribs extend continuously about the inner periphery of theliner in a circumferential direction.

The present invention relates to a new and novel rotary pressure Vessel,and more particularly to a Yankee drier or the like having a ribbedliner of high thermal conductance on the inner periphery thereof.

The present invention is particularly directed to Yankee driers employedfor drying a web of paper which is run over the smooth outer surface ofthe Yankee drier shell to be smoothed, dried or glossed by theapplication of heat, and in some instances pressure.

Steam is admitted under pressure into the interior of the shell, and theshell is particularly designed to transfer the heat of condensationthrough the shell to the web being treated. Drying of paper and the likein web form requires high uniformity of heat transfer to the variousportions of the shell to obtain the desired results.

It has been proposed in the prior art to provide integral ribs on theinner surface of the iron drier shell. The present invention representsan improvement over this type of arrangement.

In the present invention, a liner is provided on the inner surface ofthe outer cast iron drier shell, this liner having higher thermalconductivity than the cast iron portion of the shell. This liner is alsoprovided with ribs of certain critical dimensions in order to provideoptimum performance of the drier.

The provision of this liner serves to increase the rate of heat transferthrough the shell, the liner preferably being made of a substance suchas aluminum or copper and the like and being metallurgically bonded tothe inside surface of the outer cast iron shell portion. With thisarrangement, it has also been found that the rate of heat transfer isnot affected by normal variations in condensate thickness or oscillationin condensate flow that occur above rimming speed of the drier.

The ribs formed on the liner limit the flow of condensate within thedrier to a circumferential flow and ensure that no substantiallongitudinal flow will occur.

Substantially uniform heat transfer to all portions of the outsidesurface of the shell is obtained, and at the same time the excellentstrength and wear characteristics of the cast iron outer shell portionare maintained. The liner also serves to strengthen the shell somewhat,thereby adding to the structural rigidity of the construction.

The liner also serves to fill up small pores formed on the inner surfaceof the cast iron outer shell portion, thereby enhancing uniform heattransfer to a paper web pass- 3,367,042 Patented Feb. 6, 1968 ing overthe shell, and further preventing leakage of steam through the outershell portion. This eliminates the use of plugs in the cast iron driershell.

The ribs are provided with a particular thickness and are spaced apart aparticular distance in order to provide the desired results, the ribshaving opposite side surfaces which extend substantially radiallyinwardly, the inner surfaces of the ribs being tapered to an apex or ofcrowned configuration. This apex or crown at the inner portion of eachof the ribs aids in shedding condensate from the rib when the drieroperates above rimming speed, thereby increasing the rate of heattransfer through the liner at such speeds.

The liner may be formed of various materials of high thermalconductivity such as aluminum or copper. These substances are desirabledue to their availability and further their ability to adhere to a castiron outer shell portion in a casting process.

An object of the present invention is to provide a new and novel Yankeedrier or the like of such a construction as to provide an increased rateof heat transfer through the shell thereof.

Another object of the invention is the provision of a Yankee drier orthe like wherein the rate of heat transfer is not affected by normalvariations in condensate thickness or oscillations in the condensateflow that occur above rimming speeds of the drier.

A further object of the invention is to provide a Yankee drier whichaffords substantially uniform heat transfer to all portions of theoutside surface of the shell thereof.

Yet another object of the invention is the provision of a Yankee drieror the like including supplementary means for preventing leakage ofsteam through the cast iron outer shell portion thereof, and wherein theoverall strength of the construction is increased.

Other objects and many attendant advantages of the invention will becomemore apparent when considered in connection with the specification andaccompanying drawings, wherein:

FIG. 1 is a longitudinal section through a Yankee drier according to thepresent invention;

FIG. 2 is an enlarged view of a portion of the structure shown in FIG. 1illustrating certain details thereof; and

FIG. 3 is a view similar to FIG. 2 illustrating a modified form of theinvention.

Referring now to the drawings wherein like reference charactersdesignate corresponding parts throughout the several views, FIG. 1illustrate a typical Yankee drier construction according to the presentinvention. A generally cylindrical shell is indicated generally byreference numeral 10 and includes an outer shell portion 12 formed ofcast iron or similar material and having a smooth outer peripheralsurface. A liner 14 formed preferably of aluminum or copper and the likeis metallurgically bonded to the inner periphery of shell portion 12,this liner having a plurality of ribs 15 formed on the inner portionthereof, these ribs defined in more detail hereinafter.

A first head 16 is provided at one end of the shell, and a second head18 is provided at the opposite end of the shell, these heads beingsuitably secured as by bolts 20 to the shell and forming closures forthe opposite ends thereof.

A plate 24 is bolted to head 16 and includes a journal 28 which ishollow and receives an inlet tube 30 through which steam is introducedinto the drier. Journal 28 is adapted to be rotatably supported in asuitable conventional manner. Inlet tube 30 is adapted to feed steaminto the interior of a hollow tubular portion 32 integral with plate 24.

A plate 40 is secured by bolts 42 to head 18, plate 40 including anintegral journal 44 which is hollow and which receives an outlet tube 46for removing steam from the drier as hereinafter explained. Journal 44is adapted to be suitably rotatably supported in a conventional manner.The outlet tube 46 is in communication with the hollow interior of atubular portion 48 formed integral with plate 40.

The inner ends of tubular portions 32 and 48 are provided with flanges50 and 52. which extend radially outwardly thereof and which are boltedto one another by bolts 54. A plate 55 is sandwiched between flanges 50and 52, and is secured in the operative position illustrated. Steamnozzles 56 and 58 are mounted within the outer ends of openings '60 and62 respectively formed in plate 55, whereby steam introduced through theinlet tube passes through the tubular portion 32 and thence outwardlythrough openings 60 and 62 in steam nozzles 56 and 58 into the interiorof the drier shell.

Means for removing condensate from the interior of the shell includes asupport member 70 extending radially outwardly from the flange portion52 and supporting a longitudinally extending hollow pipe 72 supported atbrackets 74 and 76 at the opposite ends thereof, these brackets beingmounted upon heads 16 and 18 respectively. A plurality of straws ortubes 78 extend from pipe 72 into the bottom of the grooves providedbetween adjacent ribs 15 formed on the liner 14, these tubes serving topick up condensate in the grooves which is then carried to the pipe 72and thence through a radially extending conduit 80 to the interior ofthe tubular portion 48.

A second support member 84 extends radially outwardly from flange 52 andsupports a hollow pipe 86 at a position substantially diametricallyopposite to the previously described pipe 72. Pipe 86 is supported atthe opposite ends thereof by brackets 88 and 90 mounted on the heads 16and 18 respectively. A plurality of straws or tubes 92 extend radiallyoutwardly from pipe 86 into the bottom of the grooves formed betweenadjacent ones of the ribs 15 on the liner. Condensate received by tubes92, which, of course, are open at the outer ends thereof, is directed topipe 86 and thence through a radially inwardly extending conduit member94 to the interior of the hollow tubular portion 48 whereupon thecondensate may pass outwardly through the outlet tube 46.

Referring now to FIG. 2 of the drawings, an enlarged view of the lowerportion of the shell shown in FIG. 1 is illustrated wherein certaincritical dimensions of the various components are illustrated. As shownin this figure, the dimension A represents the thickness of the castiron iron outer shell portion 12. The dimension B represents the widthof an individual rib 15 in a direction extending substantially parallelwith the longitudinal axis of the shell. The dimension C represents thespace between facing side surfaces 100 of adjacent ones of said ribs, itbeing noted that these side surfaces extend substantially radiallyinwardly. The dimension D represents the height of the ribs, and thedimension E represents the root thickness of the liner.

The dimension A for all practical sizes of Yankee driers will lie withina range of about 0.25 inch to about 2.0 inches. The width of the rib Bshould lie within a range of bout 0.25 inch to about 1.50 inches, andwith the configuration shown in FIG. 2, wherein no ribs are formed onthe outer shell portion 12, the optimum value of the distance B is about1.25 inches.

The distance C should lie within the range of about 0.25 inch to about1.5 inches, and a spacing of about 0.5 inch is considered to be anoptimum spacing.

The dimension D should lie within the range of about 0.25 inch to about1.25 inches, and the dimension B should lie within the range of about0.001 inch to about 0.125 inch.

It will be noted that the inner surface 102 of each of the ribs istapered to an apex 104 these inner surfaces defining an angle x as seenin FIG. 2 with an adjacent side surface of the associated rib ofapproximately 15".

With the dimensions as set forth hereinabove, the arrangement has beenfound to provide optimum performance.

Referring now to FIG. 3, a modification is illustrated wherein the drieris in all respects similar to that previously described with theexception that the outer shell portion is provided with ribs. Similarparts will be given similar reference numerals primed, and it will benoted that the outer shell portion 12 is provided with spaced ribs whichextend continuously around the outer periphery thereof and which extendradially inwardly from the shell. The liner is metallurgically bonded tothe outer shell portion in this modification and is provided with aplurality of ribs 15 corresponding to the ribs 15 previously described.

The dimensions A, B, C, D and E correspond to the dimensions previouslydescribed. An additional dimension F indicates the height of the ribs100 formed on the outer shell portion.

In this modification, the dimensions A and B should lie within the sameranges as discussed previously, but with this arrangement, the optimumvalue for dimension B is about 1.5 inches. The dimensions C, D. and Eshould also be within the same ranges as previously discussed with theoptimum value of dimension C being the same. The dimension F should liewithin the range of about 0.25 inch to about 1.25 inches, and the anglex may again be 15 in this modification.

It is apparent from the foregoing that there is provided according tothe present invention a new and novel rotary pressure vessel such as aYankee drier or the like having a construction which provides anincreased rate of heat transfer through the shell thereof. The rate ofheat transfer is not affected by normal variations in condensatethickness or oscillations in condensate flow that occur above rimmingspeeds of the drier. Substantially uniform heat transfer to all portionsof the outside surface of the shell is afforded. The liner preventsleakage of steam through the cast iron outer shell portion, and furtherenhances the structural rigidity of the overall drier construction.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, and since thescope of the invention is defined by the appended claims, all

changes that fall within the metes and bounds of the.

claims or that form their functional as well as conjointly cooperativeequivalents are therefore intended to be embraced by those claims.

I claim:

1. A Yankee drier or the like comprising a generally cylindrical shell,a head at each end of said shell forming closures for opposite ends ofthe shell and including means for journalling the shell for rotationabout its longitudinal axis, said shell including an outer shellportion, a liner disposed inwardly of said outer shell portion and incontact therewith, said liner being formed of a material having higherthermal conductivity than said outer shell portion, said liner includinga plurality of spaced radially inwardly extending ribs, said ribsextending continuously about the inner periphery of said liner in acircumferential direction.

2. Apparatus as defined in claim 1, wherein said liner ismetallurgically bonded to the inner periphery of said outer shellportion.

3. Apparatus as defined in claim 1, wherein the opposite side surfacesof each of said ribs on said liner extend substantially radiallyinwardly, and the inner surface of each of said ribs tapers inwardly toan apex.

4. Apparatus as defined in claim 1, wherein the space between the facingsurfaces of adjacent ribs in a direction parallel with the longitudinalaxis of said shell is within the range of about 0.25 inch to about 1.25inches.

5. Apparatus as defined in claim 1, wherein the width of each of saidribs in a direction extending parallel with the longitudinal axis ofsaid shell is within the range of about 0.25 inch to about 1.50 inches.

6. Apparatus as defined in claim 1, wherein the space between facingsurface of adjacent ribs in a direction extending parallel with thelongitudinal axis of said shell is within the range of about 0.25 inchto about 1.25 inches, and the width of said ribs in a directionextending parallel with the longitudinal axis of said shell is withinthe range of about 0.25 inch to about 1.50 inches.

7. Apparatus as defined in claim 1, wherein said outer shell portiondefines a smooth outer peripheral surface, said outer shell portionbeing formed of cast iron, said liner being metallurgically bonded tothe inner periphery of said outer shell portion, each of said ribshaving opposite side surfaces extending radially inwardly and includingan inner surface which is tapered to an apex, the space between thefacing side surfaces of adjacent ribs in a direction extendingsubstantially parallel with the longitudinal axis of said shell beingwithin the range of about 0.25 inch to about 1.25 inches, and the widthof each of said ribs in a direction extending substantially parallelwith the longitudinal axis of said shell being within the range of about0.25 inch to about 1.50 inches.

8. Apparatus as defined in claim 7, wherein said space is approximately0.5 inch.

9. Apparatus as defined in claim 7, wherein said outer shell portion hasradially inwardly directed ribs formed thereon, the radial dimension ofsaid last-mentioned ribs being within the range of about 0.25 inch toabout 1.25 inches.

10. Apparatus as defined in claim 9, wherein each of said ribs has awidth of approximately 1.50 inches.

References Cited UNITED STATES PATENTS 1,763,629 6/1930 Hopkins 34110 X2,141,377 12/1938 Chylinski 34119 X 2,259,024 10/1941 Cleveland 165893,241,251 3/1966 Justus et a1. 34-124 FOREIGN PATENTS 939,926 10/1963Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner.

